Java event handling

im new to java & self-taught, so i may be incorrect. i wish to create a stand-alone logon dialog (frame) that can be invoked prior to any server program. The user would enter server, userid, & password, then press logon button. the logic would try to connect and return pass/fail, & 3 logon values above via a vector.
i find that action performed(actionevent e cannot return a vector (or anything else). I want my logic in the server app, not my logon dialog. there must be a way.
thanks in advance to any who help. please be kind. i've only been writing code since 1965.

Also have a look at the PropertyChangeSupport class and its
counterpart the PropertyChangeListener interface.
kind regards,
Jos

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Call to pl/sql from java event-handler

How can I call pl/sql procedure or function from java-script event handler
Thanks,
Anna

Anna,
You cannot call any arbitrary PLSQL code from the forms, only "standard"/custom event handlers can be called through do_event Javascript fuction, syntax :
do_event(this.form,this.name,1,'ON_CLICK,'');
where:
1 - button intstance, if you have more than one instance of the same button on the screen this should be 2,3,4.....
'ON_CLICK' - is the predefined event type
'' - the last argument is any user defined string which will passed down to the PLSQL event handler.
Thanks,
Dmitry
null

Java Event Handling in JSP Pages

Dear All:
This is what I wanna do. when user enters text in my <input type="text" ... > in my JSP page, I want to take this user entered data and convert it in another language simultaneously as the user is inputting text in another textarea.
Right now the only choice I have is onChange="convert()" Javascript function.
But I dont want to use Javascript as I already have a Java class which does that for the Swing GUI client.
Is their a way i can embed java for event handling in jsp.
thanks,
Chetan

only if you use an applet, javascript, etc.
remember, jsp is server-side, not client-side
what the client sees is html or whatever (i.e. static content)

DataObject defined into uix page. Can I get it from Java event handler?

I have in my uix page following code:
<dataScope>
<provider>
<data name="MyDataObject">
<method class="mypackage.MyClass" method="getMyDataObject"/>
</data>
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Thank you.

Only by directly accessing mypackage.MyClass.getMyDataObject(), it's not
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Teaching Event Handling

Hi,
I need to tech to a small group of students Java Event Handling.
I do not want to go deep. Their level is not high. Maybe some custom events and event listeners (mainly ActionListeners, ItemListeners and WindowListeners).
I need to find a good teaching example. A simple application that will let them understand how Event Handling is done, the right way.
The tutorial consists of 2 parts.
I do not ask for code (although it is welcome). I ask for some ideas on how to do it and one exercise that can be taught in 2 steps (courses).
Any ideas would be appreciated!
Chris

Hi,
You can give 2 basic exmples of even handling
1. Click on button: 'Action Performed', which will give idea of about how controls are handled.
2. Tree Example: Expansion & Collapse all of children nodes, which will give overview of delegation of events and calling some events programmatically.
I think this will give students a rough but good idea about events, though they need not dig up in deep.
Best Regards,
Yashodhan

Event Handling with Java API.: Adding to a hierarchy table throws 2events

I´m having some problems with the event handling. I´ve registered a Class with extends AbstractDataListener as EventListener. When there are changes in the product hierarchy table, some extra work should be done. However if i add a new record into the hierarchy, two events are fired.
DEBUG DataEventListener.java:123 - Added:Development;PRODUCT_HIERARCHY;R17;Getra?nke, SEW
DEBUG DataEventListener.java:123 - Added:Development;PRODUCT_HIERARCHY;R17;32 Zoll, B&R
DEBUG DataEventListener.java:123 - Added:Development;PRODUCT_HIERARCHY;R18;56 Zoll, Lenze
DEBUG DataEventListener.java:123 - Added:Development;PRODUCT_HIERARCHY;R18;20 Zoll, allgemein
In this case, i added the records "32 Zoll, B&R" and then "20 Zoll, allgemein". As you can see in both cases two events are fired and the first event seems to come with wrong data. The reported id for the newly created record is R17. For the logging, i did lookup the entry in the hierarchy table by id and use the displayvalue of the record. But the first event always shows the displayvalue from some already existing entry.
How can i avoid duplicate events or if this is not possible, how i can recognize that the display value of the first event is not valid.

I have not tetsted it yet, because I'm waiting for my server to be updated, but SAP told me that the API version 5.5.42.67 should fix the problem.
Thanks for your post.

*ACTUAL* event handling mechanism in java

Hi there! Could someone please help me find resources that explain how EXACTLY the event handling mechanism works in java?
My searches on google and java.sun take me to pages that explain how to code or something close to that. But what I actually want to know is how is all this handled BY Java- how does the event source or VM know how/when to fire and event? how the event is fired? how do objects keep track of the listener objects?...and all the background stuff like that.
I've downloaded the Java source code, too. But it seems like an ocean to me to wade through. Would be a great help if someone could 'point out the right path'.
Thank you very much!

Hi there! Could someone please help me find
resources that explain how EXACTLY the event
handling mechanism works in java?My counter question is why do you care how EXACTLY the mechanism works? It works, and that's all most people need to know.
How it works is an implementation issue, likely to change from release to release, or as more efficient mechanisms are discovered.
But what I actually want to know is how is all this
handled BY Java- how does the event source or VM
know how/when to fire and event?Native peers attached to a component (AWT) or the frame (Swing) notify Java that an event has occurred in some way. (This will likely change somewhat from platform to platform)
An AWTEvent is created to represent the native event (Swing requiring more overhead to locate the source of the event) which is added to the EventQueue.
how the event is fired? how do objects keep track of
the listener objects?...and all the background stuff like
that.The above is done on a native thread - not the event thread. The event thread is sitting in the event queue waiting for an event to come along. It processes events in the queue and sends them to the object which "generated" them. This object informs each of its listeners in turn about the event.
Objects keep track of listeners however they want. AWT objects seem to use java.awt.AWTEventMulticaster. Swing objects seem to use an javax.swing.event.EventListenerList. I tend to use multiple ArrayLists.
Note that native events are sent through the EventQueue because they originate from non-event-thread threads. Often when specialising events, in particular sending custom events in response to, say, a button press, the event firing will be done in-place, since it is already in the event thread. Custom events that originate from outside the event thread are customarily added to the EventQueue with EventQueue.invokeLater or invokeAndWait.
This is from inspection of the Java 1.3 source (specifically java.awt.Button and javax.swing.JComponent) and knowledge of the APIs.

Java 1 vs. Java 2 Event Handling

Prelude: This question relates to writing code for event handling.
Java 1 is based on a hierarchy model to handle events, ie. inheritance from superclasses. Java 2 uses delagation event handling method. Java 2 code will not compile if it includes Java 1 code still modeled according to Java 1 event handling.
Question:
Is it generally easier to start completely over in trying to convert Java 1 code into Java 2 code by not retaining any Java 1 code and begin reconceptualizing what is needed for a conversion to Java 2?

From what I understand java2 should support both models, however not both at the same time, you cant mix the modles...
I also think that the older models methods or at least most have been depreciated, meaning that the old model will, if it hasnt allready in the latest release, dissapear.. For that single reason I would recommend updating the event model to the delegation model if you hope to keep it around and running for years to come. You gain a bit by doing this since the newer model is much faster!!!

Difference in event handling between Java and Java API

could anyone list the differences between Java and java-API in event handling??
thanks,
cheers,
Hiru

the event handling mechanisms in java language
features and API (java Application Programming
Features)features .no library can work without a
language and no language has event handling built in.
I am trying to compare and contrast the event
handling mechanisms in the language and library
combinations such as java/ java API.
all contributions are welcome!
thanks
cheersSorry, I'm still not getting it. I know what Java is, and I know what I think of when I hear API. (Application Programming Interface.) The API is the aggregation of all the classes and methods you can call in Java. If we agree on that, then the event handling mechanisms in Java and its API are one and the same.
So what do you want to know?
%

How can I execute an external program from within a button's event handler?

I am using Tomcat ApacheTomcat 6.0.16 with Netbeans 6.1 (with the latest JDK/J2EE)
I need to execute external programs from an event handler for a button on a JSF page (the program is compiled, and extremely fast compared both to plain java and especially stored procedures written in SQL).
I tried what I'd do in a standalone program (as shown in the appended code), but it didn't work. Instead I received text saying the program couldn't be found. This error message comes even if I try the Windows command "dir". I thought with 'dir' I'd at least get the contents of the current working directory. :-(
I can probably get by with cgi on Apache's httpd server (or, I understand tomcat supports cgi, but I have yet to get that to work either), but whatever I do I need to be able to do it from within the button's event handler. And if I resort to cgi, I must be able to maintain session jumping from one server to the other and back.
So, then, how can I do this?
Thanks
Ted
NB: The programs that I need to run do NOT take input from the user. Rather, my code in the web application processes user selections from selection controls, and a couple field controls, sanitizes the inoputs and places clean, safe data in a MySQL database, and then the external program I need to run gets safe data from the database, does some heavy duty number crunching, and puts the output data into the database. They are well insulated from mischeif.
NB: In the following array_function_test.pl was placed in the same folder as the web application's jsp pages, (and I'd tried WEB-INF - with the same result), and I DID see the file in the application's war file.
        try {
            java.lang.ProcessBuilder pn = new java.lang.ProcessBuilder("array_function_test.pl");
            //pn.directory(new java.io.File("K:\\work"));
            java.lang.Process pr = pn.start();
            java.io.BufferedInputStream bis = (java.io.BufferedInputStream)pr.getInputStream();
            String tmp = new String("");
            byte b[] = new byte[1000];
            int i = 0;
            while (i != -1) {
                bis.read(b);
                tmp += new String(b);
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            getSelectionsDisplayTextArea().setText(getSelectionsDisplayTextArea().getText() + "\n\n" + ex.getMessage());
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Hi Fonsi!
One way to execute an external program is to use the System Exec.vi. You find it in the functions pallet under Communication.
/Thomas

Swing: when trying to get the values from a JTable inside an event handler

Hi,
I am trying to write a graphical interface to compute the Gauss Elimination procedure for solving linear systems. The class for computing the output of a linear system already works fine on console mode, but I am fighting a little bit to make it work with Swing.
I put two buttons (plus labels) and a JTextField . The buttons have the following role:
One of them gets the value from the JTextField and it will be used to the system dimension. The other should compute the solution. I also added a JTable so that the user can type the values in the screen.
So whenever the user hits the button Dimensiona the program should retrieve the values from the table cells and pass them to a 2D Array. However, the program throws a NullPointerException when I try to
do it. I have put the code for copying this Matrix inside a method and I call it from the inner class event handler.
I would thank you very much for the help.
Daniel V. Gomes
here goes the code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import AdvanceMath.*;
public class MathF2 extends JFrame {
private JTextField ArrayOfFields[];
private JTextField DimOfSis;
private JButton Calcular;
private JButton Ativar;
private JLabel label1;
private JLabel label2;
private Container container;
private int value;
private JTable DataTable;
private double[][] A;
private double[] B;
private boolean dimensionado = false;
private boolean podecalc = false;
public MathF2 (){
super("Math Calcs");
Container container = getContentPane();
container.setLayout( new FlowLayout(FlowLayout.CENTER) );
Calcular = new JButton("Resolver");
Calcular.setEnabled(false);
Ativar = new JButton("Dimensionar");
label1 = new JLabel("Clique no bot�o para resolver o sistema.");
label2 = new JLabel("Qual a ordem do sistema?");
DimOfSis = new JTextField(4);
DimOfSis.setText("0");
JTable DataTable = new JTable(10,10);
container.add(label2);
container.add(DimOfSis);
container.add(Ativar);
container.add(label1);
container.add(Calcular);
container.add(DataTable);
for ( int i = 0; i < 10 ; i ++ ){
for ( int j = 0 ; j < 10 ; j++) {
DataTable.setValueAt("0",i,j);
myHandler handler = new myHandler();
Calcular.addActionListener(handler);
Ativar.addActionListener(handler);
setSize( 500 , 500 );
setVisible( true );
public static void main ( String args[] ){
MathF2 application = new MathF2();
application.addWindowListener(
new WindowAdapter(){
public void windowClosing (WindowEvent event)
System.exit( 0 );
private class myHandler implements ActionListener {
public void actionPerformed ( ActionEvent event ){
if ( event.getSource()== Calcular ) {
if ( event.getSource()== Ativar ) {
//dimensiona a Matriz A
if (dimensionado == false) {
if (DimOfSis.getText()=="0") {
value = 2;
} else {
value = Integer.parseInt(DimOfSis.getText());
dimensionado = true;
Ativar.setEnabled(false);
System.out.println(value);
} else {
Ativar.setEnabled(false);
Calcular.setEnabled(true);
podecalc = true;
try {
InitValores( DataTable, value );
} catch (Exception e) {
System.out.println("Erro ao criar matriz" + e );
private class myHandler2 implements ItemListener {
public void itemStateChanged( ItemEvent event ){
private void InitValores( JTable table, int n ) {
A = new double[n][n];
B = new double[n];
javax.swing.table.TableModel model = table.getModel();
for ( int i = 0 ; i < n ; i++ ){
for (int j = 0 ; j < n ; j++ ){
Object temp1 = model.getValueAt(i,j);
String temp2 = String.valueOf(temp1);
A[i][j] = Double.parseDouble(temp2);

What I did is set up a :
// This code will setup a listener for the table to handle a selection
players.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
ListSelectionModel rowSM = players.getSelectionModel();
rowSM.addListSelectionListener(new Delete_Player_row_Selection(this));
//Class will take the event and call a method inside the Delete_Player object.
class Delete_Player_row_Selection
implements javax.swing.event.ListSelectionListener
Delete_Player adaptee;
Delete_Player_row_Selection (Delete_Player temp)
adaptee = temp;
public void valueChanged (ListSelectionEvent listSelectionEvent)
adaptee.row_Selection(listSelectionEvent);
in the row_Selection function
if(ex.getValueIsAdjusting()) //To remove double selection
return;
ListSelectionModel lsm = (ListSelectionModel) ex.getSource();
if(lsm.isSelectionEmpty())
System.out.println("EMtpy");
else
int selected_row = lsm.getMinSelectionIndex();
ResultSetTableModel model = (ResultSetTableModel) players.getModel();
String name = (String) model.getValueAt(selected_row, 1);
Integer id = (Integer) model.getValueAt(selected_row, 3);
This is how I got info out of a table when the user selected it

Event Handler Error while Creating User

Hi,
I am not able to create users in OIM 11gR1 - " Event handler DemoNotificationEventResolver implemented using class/plug-in nrma.DemoNotificationEventResolver could not be loaded."
I have deleted this plugin from the "plugins" table in the database. What else am I supposed to do?

Hi,
I have deleted it from the MDS Schema. Now I am getting a different error.
<Dec 20, 2012 5:24:57 PM EST> <Error> <oracle.iam.identity.usermgmt.impl> <IAM-3050030> <An exception occurred while performing the operation.
java.util.MissingResourceException: Can't find resource for bundle java.util.PropertyResourceBundle, key IAM-301094
at java.util.ResourceBundle.getObject(ResourceBundle.java:374)
at java.util.ResourceBundle.getObject(ResourceBundle.java:371)
at java.util.ResourceBundle.getObject(ResourceBundle.java:371)
at java.util.ResourceBundle.getObject(ResourceBundle.java:371)
at java.util.ResourceBundle.getString(ResourceBundle.java:334)
at oracle.iam.ldapsync.impl.util.LDAPSyncUtil.createValidationFailedException(LDAPSyncUtil.java:700)
at oracle.iam.ldapsync.impl.util.LDAPSyncUtil.generateAndValidateRDN(LDAPSyncUtil.java:824)
at oracle.iam.ldapsync.impl.eventhandlers.user.RDNPreProcessHandler.execute(RDNPreProcessHandler.java:68)
at oracle.iam.platform.kernel.impl.OrchProcessData.runPreProcessEvents(OrchProcessData.java:898)
at oracle.iam.platform.kernel.impl.OrchProcessData.runEvents(OrchProcessData.java:634)
at oracle.iam.platform.kernel.impl.OrchProcessData.executeEvents(OrchProcessData.java:227)
at oracle.iam.platform.kernel.impl.OrchestrationEngineImpl.resumeProcess(OrchestrationEngineImpl.java:664)
at oracle.iam.platform.kernel.impl.OrchestrationEngineImpl.process(OrchestrationEngineImpl.java:435)
at oracle.iam.platform.kernel.impl.OrchestrationEngineImpl.orchestrate(OrchestrationEngineImpl.java:381)
at oracle.iam.platform.kernel.impl.OrchestrationEngineImpl.orchestrate(OrchestrationEngineImpl.java:334)
at oracle.iam.identity.usermgmt.impl.UserManagerImpl.create(UserManagerImpl.java:653)
at oracle.iam.identity.usermgmt.api.UserManagerEJB.createx(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.bea.core.repackaged.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:310)

Help needed in implementing validation event handler in OIM 11g

Hello experts,
I am trying to set username policy by implementing a validation event handler in OIM 11.1.1.5.
Following are the steps followed
1. Import metadata
Created a file called Eventhandler.xml as below and imported using weblogicImportmetadata.sh
<?xml version='1.0' encoding='UTF-8'?>
<eventhandlers xmlns="http://www.oracle.com/schema/oim/platform/kernel" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.oracle.com/schema/oim/platform/kernel orchestration-handlers.xsd">
<validation-handler class="test.iam.eventhandlers.CustomValidationEventHandler" entity-type="User" operation="CREATE" name="CustomValidationEventHandler" order="1000" sync="TRUE"/>
</eventhandlers>
2. Register plugin
plugin.xml
<?xml version="1.0" encoding="UTF-8"?>
<oimplugins xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<plugins pluginpoint="oracle.iam.platform.kernel.spi.ValidationHandler">
<plugin pluginclass="test.iam.eventhandlers.CustomValidationEventHandler" version="1.0" name="CustomValidationEventHandler" />
</plugins>
</oimplugins>
Just givng sys out in the below code to check whther it is getting triggerred during user create.
package test.iam.eventhandlers;
import java.util.HashMap;
import oracle.iam.platform.Platform;
import oracle.iam.platform.context.ContextAware;
import oracle.iam.platform.kernel.ValidationException;
import oracle.iam.platform.kernel.ValidationFailedException;
import oracle.iam.platform.kernel.spi.ValidationHandler;
import oracle.iam.platform.kernel.vo.BulkEventResult;
import oracle.iam.platform.kernel.vo.BulkOrchestration;
import oracle.iam.platform.kernel.vo.Orchestration;
public class CustomValidationEventHandler implements ValidationHandler {
     @Override
     public void initialize(HashMap<String, String> arg0) {
     // TODO initialization
          System.out.println("init validate event handler");
     @Override
     public void validate(long processId, long eventId, Orchestration orchestration)
     throws ValidationException, ValidationFailedException {
          System.out.println("Beginning of validation");
          System.out.println("End of validation");
     @Override
     public void validate(long processId, long eventId, BulkOrchestration arg2)
     throws ValidationException, ValidationFailedException {
     // TODO - N/A
          System.out.println("Bulk Orchestration not yet implemented");
Now when i create a user it is not allowing and i am getting system error in the front end and in the logs i could see something below
<May 28, 2012 3:03:29 PM CEST> <Error> <oracle.iam.identity.usermgmt.impl> <IAM-3050029> <The user cannot be created due to validation errors.
oracle.iam.platform.kernel.ValidationFailedException: Event handler CustomValidationEventHandler implemented using class/plug-test.iam.eventhandlers.CustomValidationEventHandler could not be loaded.
at oracle.iam.platform.kernel.impl.OrchProcessData.runValidationEvents(OrchProcessData.java:177)
at oracle.iam.platform.kernel.impl.OrchestrationEngineImpl.validate(OrchestrationEngineImpl.java:644)
at oracle.iam.platform.kernel.impl.OrchestrationEngineImpl.process(OrchestrationEngineImpl.java:497)
at oracle.iam.platform.kernel.impl.OrchestrationEngineImpl.orchestrate(OrchestrationEngineImpl.java:444)
at oracle.iam.platform.kernel.impl.OrchestrationEngineImpl.orchestrate(OrchestrationEngineImpl.java:378)
at oracle.iam.identity.usermgmt.impl.UserManagerImpl.create(UserManagerImpl.java:656)
at oracle.iam.identity.usermgmt.api.UserManagerEJB.createx(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.bea.core.repackaged.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:310)
at com.bea.core.repackaged.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
I have implemented preprocess and postprocess event handler before with similar kind of plugin registration, metadata import and everything worked fine. Not sure what is the problem here with validation event handler.
Thanks
DK

Instead of registering the plug-in can u try placing it in the plugins folder under Oracle_IDM1/server folder.
at times restart is required. esp when the server is running in production mode.
Regards
user12841694

Can we apply an event handler only for a custom request in oim 11G?

Hi,
We would like to create a custom request for user creation, modification etc.
I saw that event handlers allow to add business rules by running java code during differents steps of processes.
I would like to know if we can trigger an event handler on a specific request and not on all user CREATION, UPDATE etc.
For example, we would like to have differents creation requests and a differents event handler on each request.
And can we add "logical" input on request form and read them in event handler?
For example, 3 inputs: day, month and year on the form which fill one user attribute "end contract date".
Regards,
Pierre

thank you Akshat,
I saw part 19 in the developper's guide. If I understand, I can change the default CreateUserRequestData to define ALL form components that will be used in my differents user creation request templates.
I can use prepopulation adapter to pre populate field with java code.
I can use the plug-in point oracle.iam.request.plugins.StatusChangeEvent to run custom java code.
But they don't mention where you can run java code for a specific creation template named "MyUserCreationTemplate1" and other java code for an other specific creation tempalate" MyUserCreationTemplate2".
That makes me think we must retrieve the template name in java code and execute the appropriate business logic.
if request name==MyUserCreationTemplate1
Edited by: user1214565 on 31 mai 2011 07:42

Applet Event Handler

Would someone please help me. I am new to applet development and I get a compile error associated with the event handling in my first ever applet code as follows:
C:\j2sdk1.4.2_01\bin>javac trajectory_j.java
trajectory_j.java:248: illegal start of expression
private class Handler implements ActionListener {
^
trajectory_j.java:248: ';' expected
private class Handler implements ActionListener {
^
2 errors
de.
This is the code:
// trajectory Analysis Program: trajectory_j.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class trajectory_j extends JApplet implements ActionListener {
     private JTextArea introductionArea, resultsArea;
     private JLabel spanLabel, chordLabel,
          thicknessLabel, massLabel, altitudeLabel, velocityLabel,
          trajectory_angleLabel, time_incrementLabel, rotation_factorLabel,
          calculationLabel, resultsLabel;
     private JTextField spanField, chordField, thicknessField,
          massField, altitudeField, velocityField, trajectory_angleField,
          time_incrementField, rotation_factorField;
     private JButton startButton, resetButton, contButton, termButton;
     String introduction_string, span_string, chord_string, thickness_string, mass_string,
          altitude_string, velocity_string, trajectory_angle_string,
          time_increment_string, rotation_factor_string, results_string;
     double span, chord, thickness, mass, altitude, velocity, trajectory_angle, time_increment,
          rotation_factor, distance, velocity_fps, elapsed_time;
     int status_a;
     int status_b;
     int status_c;
/* deletion of code segment a
          span = 0;
          chord = 0;
          thickness = 0;
          mass = 0;
          altitude = 0;
          velocity = 0;
          trajectory_angle = 0;
          time_increment = 0;
          rotation_factor = 0;
          distance = 0;
          velocity_fps = 0;
          elapsed_time = 0;
          velocity_fps = 0;
          elapsed_time = 0;
     // create objects
     public void init()
          status_a = 0;
          status_b = 0;
          status_c = 0;
          // create container & panel
          Container container = getContentPane();
          Panel panel = new Panel( new FlowLayout( FlowLayout.LEFT));
          container.add( panel );
          // set up vertical boxlayout
          Box box = Box.createVerticalBox();
          Box inputbox1 = Box.createHorizontalBox();
          Box inputbox2 = Box.createHorizontalBox();
          Box inputbox3 = Box.createHorizontalBox();
          Box buttonbox = Box.createHorizontalBox();
          introduction_string = "This is the introduction";
          // set up introduction
          introductionArea = new JTextArea( introduction_string, 10, 50 );
          introductionArea.setEditable( false );
          box.add( new JScrollPane( introductionArea ) );
          box.add( Box.createVerticalStrut (10) );
          box.add( inputbox1);
          // set up span
          spanLabel = new JLabel( "span (feet)" );
          spanField = new JTextField(5 );
          inputbox1.add( spanLabel );
          inputbox1.add( spanField );
          Dimension minSize = new Dimension(5, 15);
          Dimension prefSize = new Dimension(5, 15);
          Dimension maxSize = new Dimension(Short.MAX_VALUE, 15);
          inputbox1.add(new Box.Filler(minSize, prefSize, maxSize));
          // set up chord
          chordLabel = new JLabel( "chord (feet)" );
          chordField = new JTextField(5 );
          inputbox1.add( chordLabel );
          inputbox1.add( chordField );
          inputbox1.add(new Box.Filler(minSize, prefSize, maxSize));
          // set up thickness
          thicknessLabel = new JLabel( "thickness (feet)" );
          thicknessField = new JTextField(5 );
          inputbox1.add( thicknessLabel );
          inputbox1.add( thicknessField );
          inputbox1.add(new Box.Filler(minSize, prefSize, maxSize));
          // set up mass
          massLabel = new JLabel( "mass (slugs)" );
          massField = new JTextField(5);
          inputbox1.add( massLabel );
          inputbox1.add( massField );
          box.add( Box.createVerticalStrut (10) );
          box.add( inputbox2);
          // set up altitude
          altitudeLabel = new JLabel( "altitude (feet)");
          altitudeField = new JTextField(5 );
          inputbox2.add( altitudeLabel );
          inputbox2.add( altitudeField );
          inputbox2.add(new Box.Filler(minSize, prefSize, maxSize));
          // set up velocity
          velocityLabel = new JLabel( "velocity (Mach Number)");
          velocityField = new JTextField(5);
          inputbox2.add( velocityLabel );
          inputbox2.add( velocityField );
          inputbox2.add(new Box.Filler(minSize, prefSize, maxSize));
          // set up trajectory_angle
          trajectory_angleLabel = new JLabel( "trajectory angle ( -90 degrees <= trajectory angle <= 90 degrees )");
          trajectory_angleField = new JTextField(5);
          inputbox2.add( trajectory_angleLabel );
          inputbox2.add( trajectory_angleField );
          box.add( Box.createVerticalStrut (10) );
          box.add( inputbox3);
          Dimension minSizeF = new Dimension(70, 15);
          Dimension prefSizeF = new Dimension(70, 15);
          Dimension maxSizeF = new Dimension(Short.MAX_VALUE, 15);
          inputbox3.add(new Box.Filler(minSizeF, prefSizeF, maxSizeF));
          // set up time_increment
          time_incrementLabel = new JLabel( "time increment (seconds)" );
          time_incrementField = new JTextField(5);
          inputbox3.add( time_incrementLabel );
          inputbox3.add( time_incrementField );
          inputbox3.add(new Box.Filler(minSizeF, prefSizeF, maxSizeF));
          // set up rotation_factor
          rotation_factorLabel = new JLabel( "rotation factor ( non-negative number)" );
          rotation_factorField = new JTextField(5);
          inputbox3.add( rotation_factorLabel );
          inputbox3.add( rotation_factorField );
          inputbox3.add(new Box.Filler(minSizeF, prefSizeF, maxSizeF));
          box.add( Box.createVerticalStrut (10) );
          box.add( buttonbox);
          // set up start
          startButton = new JButton( "START" );
          buttonbox.add( startButton );
          Dimension minSizeB = new Dimension(10, 30);
          Dimension prefSizeB = new Dimension(10, 30);
          Dimension maxSizeB = new Dimension(Short.MAX_VALUE, 30);
          buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));
          // set up reset
          resetButton = new JButton( "RESET" );
          buttonbox.add( resetButton );
          buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));
          // set up cont
          contButton = new JButton( "CONTINUE" );
          buttonbox.add( contButton );
          buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));
          // set up term
          termButton = new JButton( "END" );
          buttonbox.add( termButton );
          box.add( Box.createVerticalStrut (10) );
          // set up results
          resultsArea = new JTextArea( results_string, 10, 50 );
          resultsArea.setEditable( false );
          box.add( new JScrollPane( resultsArea ) );
          // add box to panel
          panel.add( box );
          // register event handlers
          Handler handler = new Handler();
          spanField.addActionListener( handler );
          chordField.addActionListener( handler );
          thicknessField.addActionListener( handler );
          massField.addActionListener( handler );
          altitudeField.addActionListener( handler );
          velocityField.addActionListener( handler );
          trajectory_angleField.addActionListener( handler );
          time_incrementField.addActionListener( handler );
          rotation_factorField.addActionListener( handler );
          startButton.addActionListener( handler );
          resetButton.addActionListener( handler );
          contButton.addActionListener( handler );
          termButton.addActionListener( handler );
// private inner class for event handling
private class Handler implements ActionListener {
     // process handler events
     public void actionPerformed( ActionEvent event )
          // process resetButton event
          if ( event.getSource() == resetButton )
               reset();
          // process contButton event
          if ( event.getSource() == contButton )
               cont();
          // process endButton event
          if ( event.getSource() == termButton )
          // process span event
          if( event.getSource() == spanField ) {
               span = Double.parseDouble( event.getActionCommand() );
               spanField.setText( span_string );
               status_b++;
          // process chord event
          if( event.getSource() == spanField ) {
               span = Double.parseDouble( event.getActionCommand() );
               spanField.setText( chord_string );
               status_b++;
          // process thickness event
          if( event.getSource() == thicknessField ) {
               thickness = Double.parseDouble( event.getActionCommand() );
               spanField.setText( thickness_string );
               status_b++;
          // process mass event
          if( event.getSource() == massField ) {
               mass = Double.parseDouble( event.getActionCommand() );
               spanField.setText( mass_string );
               status_b++;
          // process altitude event
          if( event.getSource() == altitudeField ) {
               altitude = Double.parseDouble( event.getActionCommand() );
               spanField.setText( altitude_string );
               status_b++;
          // process velocity event
          if( event.getSource() == velocityField ) {
               velocity = Double.parseDouble( event.getActionCommand() );
               spanField.setText( velocity_string );
               status_b++;
          // process trajectory_angle event
          if( event.getSource() == trajectory_angleField ) {
               trajectory_angle = Double.parseDouble( event.getActionCommand() );
               spanField.setText( trajectory_angle_string );
               status_b++;
          // process time_increment event
          if( event.getSource() == time_incrementField ) {
               time_increment = Double.parseDouble( event.getActionCommand() );
               spanField.setText( time_increment_string );
               status_b++;
          // process rotation_factor event
          if( event.getSource() == rotation_factorField ) {
               rotation_factor = Double.parseDouble( event.getActionCommand() );
               spanField.setText( rotation_factor_string );
               status_b++;
          // process startButton event
          if ( event.getSource() == startButton && status_b == 9 ) {
               status_c = 1;
     } // end method event handler
} // end Handler class
     } // end method init
     public void strtb()
/* deletion of code segment 1
          startButton.addActionListener(
               new ActionListener() { // anonymous inner class
                    // set text in resultsArea
                    public void actionPerformed( ActionEvent event )
                    if( status_c == 1 ){
                    calculate();
                    results();
                    resultsArea.setText( results() );
/* deletion of code segment 2
                    }// end method actionPerformed1
               } // end anonymous inner class1
          ); // end call to addActionlistener1
     } // end method strtb
     public void reset()
/* deletion of code segment 3
          resetButton.addActionListener(
               new ActionListener() { // anonymous inner class
                    // set text in resultsArea
                    public void actionPerformed( ActionEvent event )
                    span_string = "";
                    chord_string = "";
                    thickness_string = "";
                    mass_string = "";
                    altitude_string = "";
                    velocity_string = "";
                    trajectory_angle_string = "";
                    time_increment_string = "";
                    rotation_factor_string = "";
                    results_string = "";
                    spanField.setText( span_string );
                    chordField.setText( chord_string );
                    thicknessField.setText( thickness_string );
                    massField.setText( mass_string );
                    altitudeField.setText( altitude_string );
                    velocityField.setText( velocity_string );
                    trajectory_angleField.setText( trajectory_angle_string );
                    time_incrementField.setText( time_increment_string );
                    rotation_factorField.setText( rotation_factor_string );
resultsArea.setEditable( true );
                    resultsArea.setText( results_string );
resultsArea.setEditable( false );
                    span = 0;
                    chord = 0;
                    thickness = 0;
                    mass = 0;
                    altitude = 0;
                    velocity = 0;
                    trajectory_angle = 0;
                    time_increment = 0;
                    rotation_factor = 0;
                    distance = 0;
                    velocity_fps = 0;
                    elapsed_time = 0;
/* deletion of code segment 4
                    } // end method actionPerformed2
               } // end anonymous inner class2
          ); // end call to addActionlistener2
     } // end method reset
     public void cont()
     //later
     public void calculate()
     distance = 1;
     altitude = 2;
     trajectory_angle = 3;
     velocity_fps = 4;
     elapsed_time = 5;
     public String results()
     results_string =
     "Distance =\t\t" + distance + " miles\n"
     + "Altitude =\t\t" + altitude + " feet\n"
     + "Trajectory Angle =\t" + trajectory_angle + " degrees\n"
     + "Velocity =\t\t" + velocity_fps + " feet per second\n"
     + "Elapsed Time =\t\t" + elapsed_time + " seconds\n"
     + "\nstatus_a = " + status_a + "\nstatus_b = "
     + status_b + "\nstatus_c = " + status_c;
     return results_string;
public void start()
if(status_a == 0 )
strtb();
if (status_b == 0)
reset();
}// end method start
} //end class trajectory_a

The following are copies of html and java source code files for a prior runnable version ( trajectory_b ) of this program which can enlighten some functionality intended by the program.
(trajectory_b.html):
<html>
<appletcode = "trajectory_b.class" width = "800" height = "600">
</applet>
</html>
(trajectory_b.java):
// trajectory Analysis Program: trajectory_b.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class trajectory_b extends JApplet implements ActionListener {
     private JTextArea introductionArea, resultsArea;
     private JLabel spanLabel, chordLabel,
          thicknessLabel, massLabel, altitudeLabel, velocityLabel,
          trajectory_angleLabel, time_incrementLabel, rotation_factorLabel,
          calculationLabel, resultsLabel;
     private JTextField spanField, chordField, thicknessField,
          massField, altitudeField, velocityField, trajectory_angleField,
          time_incrementField, rotation_factorField;
     private JButton startButton, resetButton, contButton, termButton;
     String introduction_string, span_string, chord_string, thickness_string, mass_string,
          altitude_string, velocity_string, trajectory_angle_string,
          time_increment_string, rotation_factor_string, results_string;
     double span, chord, thickness, mass, altitude, velocity, trajectory_angle, time_increment,
          rotation_factor, distance, velocity_fps, elapsed_time;
     int status_a;
     int status_b;
     int status_c;
/* deletion of code segment a
          span = 0;
          chord = 0;
          thickness = 0;
          mass = 0;
          altitude = 0;
          velocity = 0;
          trajectory_angle = 0;
          time_increment = 0;
          rotation_factor = 0;
          distance = 0;
          velocity_fps = 0;
          elapsed_time = 0;
          velocity_fps = 0;
          elapsed_time = 0;
     // create objects
     public void init()
          status_a = 0;
          status_b = 0;
          status_c = 0;
          // create container & panel
          Container container = getContentPane();
          Panel panel = new Panel( new FlowLayout( FlowLayout.LEFT));
          container.add( panel );
          // set up vertical boxlayout
          Box box = Box.createVerticalBox();
          Box inputbox1 = Box.createHorizontalBox();
          Box inputbox2 = Box.createHorizontalBox();
          Box inputbox3 = Box.createHorizontalBox();
          Box buttonbox = Box.createHorizontalBox();
          introduction_string = "This is the introduction";
          // set up introduction
          introductionArea = new JTextArea( introduction_string, 10, 50 );
          introductionArea.setEditable( false );
          box.add( new JScrollPane( introductionArea ) );
          box.add( Box.createVerticalStrut (10) );
          box.add( inputbox1);
          // set up span
          spanLabel = new JLabel( "span (feet)" );
          spanField = new JTextField(5 );
          inputbox1.add( spanLabel );
          inputbox1.add( spanField );
          Dimension minSize = new Dimension(5, 15);
          Dimension prefSize = new Dimension(5, 15);
          Dimension maxSize = new Dimension(Short.MAX_VALUE, 15);
          inputbox1.add(new Box.Filler(minSize, prefSize, maxSize));
          // set up chord
          chordLabel = new JLabel( "chord (feet)" );
          chordField = new JTextField(5 );
          inputbox1.add( chordLabel );
          inputbox1.add( chordField );
          inputbox1.add(new Box.Filler(minSize, prefSize, maxSize));
          // set up thickness
          thicknessLabel = new JLabel( "thickness (feet)" );
          thicknessField = new JTextField(5 );
          inputbox1.add( thicknessLabel );
          inputbox1.add( thicknessField );
          inputbox1.add(new Box.Filler(minSize, prefSize, maxSize));
          // set up mass
          massLabel = new JLabel( "mass (slugs)" );
          massField = new JTextField(5);
          inputbox1.add( massLabel );
          inputbox1.add( massField );
          box.add( Box.createVerticalStrut (10) );
          box.add( inputbox2);
          // set up altitude
          altitudeLabel = new JLabel( "altitude (feet)");
          altitudeField = new JTextField(5 );
          inputbox2.add( altitudeLabel );
          inputbox2.add( altitudeField );
          inputbox2.add(new Box.Filler(minSize, prefSize, maxSize));
          // set up velocity
          velocityLabel = new JLabel( "velocity (Mach Number)");
          velocityField = new JTextField(5);
          inputbox2.add( velocityLabel );
          inputbox2.add( velocityField );
          inputbox2.add(new Box.Filler(minSize, prefSize, maxSize));
          // set up trajectory_angle
          trajectory_angleLabel = new JLabel( "trajectory angle ( -90 degrees <= trajectory angle <= 90 degrees )");
          trajectory_angleField = new JTextField(5);
          inputbox2.add( trajectory_angleLabel );
          inputbox2.add( trajectory_angleField );
          box.add( Box.createVerticalStrut (10) );
          box.add( inputbox3);
          Dimension minSizeF = new Dimension(70, 15);
          Dimension prefSizeF = new Dimension(70, 15);
          Dimension maxSizeF = new Dimension(Short.MAX_VALUE, 15);
          inputbox3.add(new Box.Filler(minSizeF, prefSizeF, maxSizeF));
          // set up time_increment
          time_incrementLabel = new JLabel( "time increment (seconds)" );
          time_incrementField = new JTextField(5);
          inputbox3.add( time_incrementLabel );
          inputbox3.add( time_incrementField );
          inputbox3.add(new Box.Filler(minSizeF, prefSizeF, maxSizeF));
          // set up rotation_factor
          rotation_factorLabel = new JLabel( "rotation factor ( non-negative number)" );
          rotation_factorField = new JTextField(5);
          inputbox3.add( rotation_factorLabel );
          inputbox3.add( rotation_factorField );
          inputbox3.add(new Box.Filler(minSizeF, prefSizeF, maxSizeF));
          box.add( Box.createVerticalStrut (10) );
          box.add( buttonbox);
          // set up start
          startButton = new JButton( "START" );
          buttonbox.add( startButton );
          Dimension minSizeB = new Dimension(10, 30);
          Dimension prefSizeB = new Dimension(10, 30);
          Dimension maxSizeB = new Dimension(Short.MAX_VALUE, 30);
          buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));
          // set up reset
          resetButton = new JButton( "RESET" );
          buttonbox.add( resetButton );
          buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));
          // set up cont
          contButton = new JButton( "CONTINUE" );
          buttonbox.add( contButton );
          buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));
          // set up term
          termButton = new JButton( "END" );
          buttonbox.add( termButton );
          box.add( Box.createVerticalStrut (10) );
          // set up results
          resultsArea = new JTextArea( results_string, 10, 50 );
          resultsArea.setEditable( false );
          box.add( new JScrollPane( resultsArea ) );
          // add box to panel
          panel.add( box );
          // register event handlers
          Handler handler = new Handler();
          spanField.addActionListener( handler );
          chordField.addActionListener( handler );
          thicknessField.addActionListener( handler );
          massField.addActionListener( handler );
          altitudeField.addActionListener( handler );
          velocityField.addActionListener( handler );
          trajectory_angleField.addActionListener( handler );
          time_incrementField.addActionListener( handler );
          rotation_factorField.addActionListener( handler );
          startButton.addActionListener( handler );
          resetButton.addActionListener( handler );
          contButton.addActionListener( handler );
          termButton.addActionListener( handler );
} // end method init
     // process handler events
     public void actionPerformed( ActionEvent event )
          // process resetButton event
          if ( event.getSource() == resetButton )
               reset();
          // process contButton event
          if ( event.getSource() == contButton )
               cont();
          // process endButton event
          if ( event.getSource() == termButton )
          // process span event
          if( event.getSource() == spanField ) {
               span = Double.parseDouble( event.getActionCommand() );
               spanField.setText( span_string );
               status_b++;
          // process chord event
          if( event.getSource() == spanField ) {
               span = Double.parseDouble( event.getActionCommand() );
               spanField.setText( chord_string );
               status_b++;
          // process thickness event
          if( event.getSource() == thicknessField ) {
               thickness = Double.parseDouble( event.getActionCommand() );
               spanField.setText( thickness_string );
               status_b++;
          // process mass event
          if( event.getSource() == massField ) {
               mass = Double.parseDouble( event.getActionCommand() );
               spanField.setText( mass_string );
               status_b++;
          // process altitude event
          if( event.getSource() == altitudeField ) {
               altitude = Double.parseDouble( event.getActionCommand() );
               spanField.setText( altitude_string );
               status_b++;
          // process velocity event
          if( event.getSource() == velocityField ) {
               velocity = Double.parseDouble( event.getActionCommand() );
               spanField.setText( velocity_string );
               status_b++;
          // process trajectory_angle event
          if( event.getSource() == trajectory_angleField ) {
               trajectory_angle = Double.parseDouble( event.getActionCommand() );
               spanField.setText( trajectory_angle_string );
               status_b++;
          // process time_increment event
          if( event.getSource() == time_incrementField ) {
               time_increment = Double.parseDouble( event.getActionCommand() );
               spanField.setText( time_increment_string );
               status_b++;
          // process rotation_factor event
          if( event.getSource() == rotation_factorField ) {
               rotation_factor = Double.parseDouble( event.getActionCommand() );
               spanField.setText( rotation_factor_string );
               status_b++;
          // process startButton event
          if ( event.getSource() == startButton && status_b == 9 ) {
               strtb();
     } // end method event handler
     public void strtb()
          startButton.addActionListener(
               new ActionListener() { // anonymous inner class
                    // set text in resultsArea
                    public void actionPerformed( ActionEvent event )
                    calculate();
                    results();
                    resultsArea.setText( results() );
                    }// end method actionPerformed1
               } // end anonymous inner class1
          ); // end call to addActionlistener1
     } // end method strtb
     public void reset()
          resetButton.addActionListener(
               new ActionListener() { // anonymous inner class
                    // set text in resultsArea
                    public void actionPerformed( ActionEvent event )
                    span_string = "";
                    chord_string = "";
                    thickness_string = "";
                    mass_string = "";
                    altitude_string = "";
                    velocity_string = "";
                    trajectory_angle_string = "";
                    time_increment_string = "";
                    rotation_factor_string = "";
                    results_string = "";
                    spanField.setText( span_string );
                    chordField.setText( chord_string );
                    thicknessField.setText( thickness_string );
                    massField.setText( mass_string );
                    altitudeField.setText( altitude_string );
                    velocityField.setText( velocity_string );
                    trajectory_angleField.setText( trajectory_angle_string );
                    time_incrementField.setText( time_increment_string );
                    rotation_factorField.setText( rotation_factor_string );
resultsArea.setEditable( true );
                    resultsArea.setText( results_string );
resultsArea.setEditable( false );
                    span = 0;
                    chord = 0;
                    thickness = 0;
                    mass = 0;
                    altitude = 0;
                    velocity = 0;
                    trajectory_angle = 0;
                    time_increment = 0;
                    rotation_factor = 0;
                    distance = 0;
                    velocity_fps = 0;
                    elapsed_time = 0;
                    } // end method actionPerformed2
               } // end anonymous inner class2
          ); // end call to addActionlistener2
     } // end method reset
     public void cont()
     //later
     public void calculate()
     distance = 1;
     altitude = 2;
     trajectory_angle = 3;
     velocity_fps = 4;
     elapsed_time = 5;
     public String results()
     results_string =
     "Distance =\t\t" + distance + " miles\n"
     + "Altitude =\t\t" + altitude + " feet\n"
     + "Trajectory Angle =\t" + trajectory_angle + " degrees\n"
     + "Velocity =\t\t" + velocity_fps + " feet per second\n"
     + "Elapsed Time =\t\t" + elapsed_time + " seconds\n"
     + "\nstatus_a = " + status_a + "\nstatus_b = "
     + status_b + "\nstatus_c = " + status_c;
     return results_string;
public void start()
if(status_a == 0 )
strtb();
if (status_b == 0)
reset();
}// end method start
} //end class trajectory_b

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